Tennis ball and the like



July 5, 1932. E PENFOLD 1,865,481

TENNIS BALL AND THE LIKE Original Filed Dec. 6, 1924 2 sheet-sheet 1 INVENTOR July 5, 1932. PENFQLD 1,865,481

- TENNIS BALL AND THE LIKE Original Filed Dec. 6, 1924 2 Sheets-Sheet 2 INVEMTOR Patented July 5, 1932 UNITED STATES PATENT OFFICE ALBERT ERNEST PENFOLD, OF BIRMINGHAM, ENGLAND, ASSIGNOR TO DUNLOP TIRE AND RUBBER CORPORATION OF NEW YORK OF AMERICA, OF BUFFALO, NEW YORK, A CORPORATION TENNIS BALL AND THE Lnrn Original application filed December 6, 1924, Serial No. 754,263, and in Great Britain March 18, 1924. Divided and this application filed April 4, 1927. Serial No. 180,952.

Fig. 3 illustrates the spherical gas-tight container showing a convenient method of attachment of india rubber strips to form a rubber coating on-its external surface;

Fig. 4 illustrates the spherical gas-tight container with one strip of rubber aflixed to its surface;

Fig. 5 illustrates a spherical gas-tight container coated with rubber and unvulcanized;

Fig. 6 illustrates a section of a rubber coated container after vulcanization;

Figs. 7 and 8 illustrate a modification in which the spherical gas-tight container is composed of two cups joined together by means of a circular strip of the same or similar material as that of which the cups are formed;

Fig. 9 illustrates a ball in which the vulcanized spherical gas-tight container is covered with felt.

A is a tennis ball constructed from a thin hollow sphere B of semi-rigid character such as can be obtained from gutta percha or balata or a rubber mixture containing a proportion of gutta percha and/or balata and inflated to the required degree by the provision therein of a suitable gas. The said hollow sphere B may be coated with a suitablelayer of soft rubber laid on in the usual form of strips C, Figs. 3, 4 and 5, and after it has been vulcanized a suitable coating of felt may be applied to form the outer covering of the ball A.

The hollow sphere Bis preferably formed of two hemispherical cups b1, 122, or it may be formed of two or more component parts y comprising two cups. A suitable material from which to form the said component parts of the hollow sphere B is a prepared mixture containing Per cent by weight Purified balata 25 Washed balata Smoked sheet rubber 3O Sulphur 10 ,Zinc oxide from which all traces of grit or other foreign matter of similar character have been removed.

Such material suitably prepared is preferably moulded in the form of cups b1, b2, the

cup 61 being of hemispherical shape, whilst the cup 62 is of similar shape provided with an overlapping ridge e. The cup 61 may be providedwith a suitable marking to indicate when it is properly seated upon the inside of the overlapping ridge e.

A convenient method of moulding the cups b1, 62 isto extrude the material or dough containing gutta percha and/or balata of which they are formed in a condition in which it is softened under gentle heat, into cord form, and whilst the cord is maintained in a soft plastic state, to cut it into pieces of the correct weight and to place the pieces in warm moulds wherein they are pressed into the desired shape, with the material evenly distributed.

Although the complete spherical gas-tight container may be supplied with gas by injecting the same after vulcanization, I prefer to use a plugless ball inflated by the generation of gas produced from gas producing chemicals within it during the process of vulcanization. Satisfactory results are obtained by placing a mixture of 0.4 grammes of sodium nitrate and 0.4 grammes of ammonium chloride to which mixture three or four drops of water have been added in one of thecups b1, b2, the rims of which are cleaned with a petroleum spirit or other cleaning solvent and smeared with a solution of rubber dissolved in petroleum spirit and fitted and joined together.

The cups b1, 122, or component parts of the spherical container B, being of semi-rigid character are conveniently andled during the operations and very little skill on the part of the operative is required to ensure accuracy of manipulation and perfect jointing. The hollow spherical gas-tight container B thus formed is then allowed to stand until the rubber jointing solution is dry when it will be found that both cups 121 and 122 have contracted together round the seam, giving a satisfactory joint and producing a semirigid container-on which to apply when desired a coating of soft rubber, and after vulcanization it will be found that the semirigidity of the container has disappeared and under the influence of the inflation gas has become extremely resilient.

In making the shells b1, b2, and after vulcanizing the container B, it is necessary to thoroughly cool the mould before the articles are removed therefrom.

This is specially important after vulcanization because the gas content is influenced by changes of temperature, and it is necessary to avoid unrestricted expansion of the gas contained therein under the influence of heat and the consequent production of oversized balls.

As above stated the gas container may before or after vulcanization be coated with a covering of rubber applied in any convenient manner when desired. V

A suitable covering of felt or other material may be applied to the outer surface of the container when desired in any convenient manner.

In Figs. 7 and 8 I have illustrated a modification m which the container is constructed of three component parts comprising two cups b1, b2, with an intermediate piece 123.

Tennis balls constructed according to my invention and as herein described possess great resiliency, are extremely durable and offer great resistance to wear. Moreover by their construction and the method thereof they can be manufactured by unskilled 0 eratives so as to retain their inflation gas t us reducing to a minimum the very large proortion of rejects which has hitherto been inseparable from the production of tennis balls and they can be relied upon not to deteriorate during the time they are stored be tween manufacture and use.

Though I have described with great particularity of detail certain embodiments of my invention, yet it is not to be understood therefrom that the invention is restricted to the particular embodiments disclosed. Vari- -ousmodifications may be made by those skilled'in the art without departing from the invention as defined in the What I claim is:

ollowing claims.

1. A tennis ball gas container comprising component parts of non-porous, non-rigid material com osed of a rubber mixture containing a su stantial percentage of a gum such as gutta percha or balata.

2. A tennis ball gas container comprising component parts of non-porous, non-rigid material composed of approximately 30 percent by weight of rubber, 25 percent by weight of purified balata and 15 percent of washed balata.

3. A tennis ball gas container comprising component parts of non-porous, non-rigid material composed of a rubber mixture containing a substantial percentage of a gum such as gutta percha or balata, said parts being joined together with a gas-tight joint.

4. A gas container for tennis balls composed-of parts of non-porous, non-rigid material joined together with gas-tight joints, said non-rigid material being composed of an ndia rubber mixture containing at least 25 ,percent by weight of a gum such as gutta percha or balata.

5. A tennis ball comprising av gas container made in accordance with claim 1, molded and vulcanized and provided with an outer covering of felt or the like.

6. A tennis ball comprising a gas container as defined in claim 2, and molded and vulcanized and provided with an outer covering of felt or the like.

7. A gas filled container of the type described which comprises walls havin component parts of non-porous, non-rigid material composed of a rubber mixture containing substantial percentages of a gum such as gutta percha or balata, and having a coating of soft rubber.

8. A gas filled container of the type described having walls comprising a vulcanized mixture of rubber and balata in proportions of approximately the same magnitude.

9. A tennis ball comprising a relatively thin walled hollow gas filled container composed of a mixture of rubber and'balata, in proportions of substantially or approximately the same magnitude and a relatively thicker covering of rubber vulcanized thereto.

10. A tennis ball comprising a relatively thin walled hollow gas filled container composed of two parts united by a gas-tight joint, said partsbeing composed of a mixture of rubber and balata with a small percentage of a vulcanizing agent incorporated therein, and a relatively thicker layer of rubber comprising separate pieces vulcanized to said container with their joints displaced relatively to the joint between the parts of the container.

In witness whereof, I have hereunto signed my name.

ALBERT ERNEST PENFOLD. 

